function project3D(x, y, z, vars) {

	var p, d;
	x -= vars.camX;
	y -= vars.camY - 8;
	z -= vars.camZ;
	p = Math.atan2(x, z);
	d = Math.sqrt(x * x + z * z);
	x = Math.sin(p - vars.yaw) * d;
	z = Math.cos(p - vars.yaw) * d;
	p = Math.atan2(y, z);
	d = Math.sqrt(y * y + z * z);
	y = Math.sin(p - vars.pitch) * d;
	z = Math.cos(p - vars.pitch) * d;
	var rx1 = -1000;
	var ry1 = 1;
	var rx2 = 1000;
	var ry2 = 1;
	var rx3 = 0;
	var ry3 = 0;
	var rx4 = x;
	var ry4 = z;
	var uc = (ry4 - ry3) * (rx2 - rx1) - (rx4 - rx3) * (ry2 - ry1);
	var ua = ((rx4 - rx3) * (ry1 - ry3) - (ry4 - ry3) * (rx1 - rx3)) / uc;
	var ub = ((rx2 - rx1) * (ry1 - ry3) - (ry2 - ry1) * (rx1 - rx3)) / uc;
	if (!z) z = 0.000000001;
	if (ua > 0 && ua < 1 && ub > 0 && ub < 1) {
		return {
			x: vars.cx + (rx1 + ua * (rx2 - rx1)) * vars.scale,
			y: vars.cy + y / z * vars.scale,
			d: (x * x + y * y + z * z)
		};
	} else {
		return { d: -1 };
	}
}


function elevation(x, y, z) {

	var dist = Math.sqrt(x * x + y * y + z * z);
	if (dist && z / dist >= -1 && z / dist <= 1) return Math.acos(z / dist);
	return 0.00000001;
}


function rgb(col) {

	col += 0.000001;
	var r = parseInt((0.5 + Math.sin(col) * 0.5) * 16);
	var g = parseInt((0.5 + Math.cos(col) * 0.5) * 16);
	var b = parseInt((0.5 - Math.sin(col) * 0.5) * 16);
	return "#" + r.toString(16) + g.toString(16) + b.toString(16);
}


function interpolateColors(RGB1, RGB2, degree) {

	var w2 = degree;
	var w1 = 1 - w2;
	return [w1 * RGB1[0] + w2 * RGB2[0], w1 * RGB1[1] + w2 * RGB2[1], w1 * RGB1[2] + w2 * RGB2[2]];
}


function rgbArray(col) {

	col += 0.000001;
	var r = parseInt((0.5 + Math.sin(col) * 0.5) * 256);
	var g = parseInt((0.5 + Math.cos(col) * 0.5) * 256);
	var b = parseInt((0.5 - Math.sin(col) * 0.5) * 256);
	return [r, g, b];
}


function colorString(arr) {

	var r = parseInt(arr[0]);
	var g = parseInt(arr[1]);
	var b = parseInt(arr[2]);
	return "#" + ("0" + r.toString(16)).slice(-2) + ("0" + g.toString(16)).slice(-2) + ("0" + b.toString(16)).slice(-2);
}


function process(vars) {


	if (vars.points.length < vars.initParticles) for (var i = 0; i < 5; ++i) spawnParticle(vars);
	var p, d, t;

	p = Math.atan2(vars.camX, vars.camZ);
	d = Math.sqrt(vars.camX * vars.camX + vars.camZ * vars.camZ);
	d -= Math.sin(vars.frameNo / 80) / 25;
	t = Math.cos(vars.frameNo / 300) / 165;
	vars.camX = Math.sin(p + t) * d;
	vars.camZ = Math.cos(p + t) * d;
	vars.camY = -Math.sin(vars.frameNo / 220) * 15;
	vars.yaw = Math.PI + p + t;
	vars.pitch = elevation(vars.camX, vars.camZ, vars.camY) - Math.PI / 2;

	var t;
	for (var i = 0; i < vars.points.length; ++i) {

		x = vars.points[i].x;
		y = vars.points[i].y;
		z = vars.points[i].z;
		d = Math.sqrt(x * x + z * z) / 1.0075;
		t = .1 / (1 + d * d / 5);
		p = Math.atan2(x, z) + t;
		vars.points[i].x = Math.sin(p) * d;
		vars.points[i].z = Math.cos(p) * d;
		vars.points[i].y += vars.points[i].vy * t * ((Math.sqrt(vars.distributionRadius) - d) * 2);
		if (vars.points[i].y > vars.vortexHeight / 2 || d < .25) {
			vars.points.splice(i, 1);
			spawnParticle(vars);
		}
	}
}

function drawFloor(vars) {

	var x, y, z, d, point, a;
	for (var i = -25; i <= 25; i += 1) {
		for (var j = -25; j <= 25; j += 1) {
			x = i * 2;
			z = j * 2;
			y = vars.floor;
			d = Math.sqrt(x * x + z * z);
			point = project3D(x, y - d * d / 85, z, vars);
			if (point.d != -1) {
				size = 1 + 15000 / (1 + point.d);
				a = 0.15 - Math.pow(d / 50, 4) * 0.15;
				if (a > 0) {
					vars.ctx.fillStyle = colorString(interpolateColors(rgbArray(d / 26 - vars.frameNo / 40), [0, 128, 32], .5 + Math.sin(d / 6 - vars.frameNo / 8) / 2));
					vars.ctx.globalAlpha = a;
					vars.ctx.fillRect(point.x - size / 2, point.y - size / 2, size, size);
				}
			}
		}
	}
	vars.ctx.fillStyle = "#82f";
	for (var i = -25; i <= 25; i += 1) {
		for (var j = -25; j <= 25; j += 1) {
			x = i * 2;
			z = j * 2;
			y = -vars.floor;
			d = Math.sqrt(x * x + z * z);
			point = project3D(x, y + d * d / 85, z, vars);
			if (point.d != -1) {
				size = 1 + 15000 / (1 + point.d);
				a = 0.15 - Math.pow(d / 50, 4) * 0.15;
				if (a > 0) {
					vars.ctx.fillStyle = colorString(interpolateColors(rgbArray(-d / 26 - vars.frameNo / 40), [32, 0, 128], .5 + Math.sin(-d / 6 - vars.frameNo / 8) / 2));
					vars.ctx.globalAlpha = a;
					vars.ctx.fillRect(point.x - size / 2, point.y - size / 2, size, size);
				}
			}
		}
	}
}

function sortFunction(a, b) {
	return b.dist - a.dist;
}

function draw(vars) {

	vars.ctx.globalAlpha = .15;
	vars.ctx.fillStyle = "#000";
	vars.ctx.fillRect(0, 0, canvas.width, canvas.height);

	drawFloor(vars);

	var point, x, y, z, a;
	for (var i = 0; i < vars.points.length; ++i) {
		x = vars.points[i].x;
		y = vars.points[i].y;
		z = vars.points[i].z;
		point = project3D(x, y, z, vars);
		if (point.d != -1) {
			vars.points[i].dist = point.d;
			size = 1 + vars.points[i].radius / (1 + point.d);
			d = Math.abs(vars.points[i].y);
			a = .8 - Math.pow(d / (vars.vortexHeight / 2), 1000) * .8;
			vars.ctx.globalAlpha = a >= 0 && a <= 1 ? a : 0;
			vars.ctx.fillStyle = rgb(vars.points[i].color);
			if (point.x > -1 && point.x < vars.canvas.width && point.y > -1 && point.y < vars.canvas.height) vars.ctx.fillRect(point.x - size / 2, point.y - size / 2, size, size);
		}
	}
	vars.points.sort(sortFunction);
}


function spawnParticle(vars) {

	var p, ls;
	pt = {};
	p = Math.PI * 2 * Math.random();
	ls = Math.sqrt(Math.random() * vars.distributionRadius);
	pt.x = Math.sin(p) * ls;
	pt.y = -vars.vortexHeight / 2;
	pt.vy = vars.initV / 20 + Math.random() * vars.initV;
	pt.z = Math.cos(p) * ls;
	pt.radius = 200 + 800 * Math.random();
	pt.color = pt.radius / 1000 + vars.frameNo / 250;
	vars.points.push(pt);
}

function frame(vars) {

	if (vars === undefined) {
		var vars = {};
		vars.canvas = document.querySelector("#canvas_web01");
		vars.ctx = vars.canvas.getContext("2d");
		vars.canvas.width = document.body.clientWidth;
		vars.canvas.height = document.body.clientHeight;
		window.addEventListener("resize", function () {
			vars.canvas.width = document.body.clientWidth;
			vars.canvas.height = document.body.clientHeight;
			vars.cx = vars.canvas.width / 2;
			vars.cy = vars.canvas.height / 2;
		}, true);
		vars.frameNo = 0;

		vars.camX = 0;
		vars.camY = 0;
		vars.camZ = -14;
		vars.pitch = elevation(vars.camX, vars.camZ, vars.camY) - Math.PI / 2;
		vars.yaw = 0;
		vars.cx = vars.canvas.width / 2;
		vars.cy = vars.canvas.height / 2;
		vars.bounding = 10;
		vars.scale = 500;
		vars.floor = 26.5;

		vars.points = [];
		vars.initParticles = 700;
		vars.initV = .01;
		vars.distributionRadius = 800;
		vars.vortexHeight = 25;
	}

	vars.frameNo++;
	requestAnimationFrame(function () {
		frame(vars);
	});

	process(vars);
	draw(vars);
}
frame();